Bearing assemblies of this type are intended for the radial and axial mounting of shafts in a housing or of housings on a shaft. In this invention, shafts are understood as meaning all conceivable machine elements, such as driven and driving shafts/shaft ends, axles and consequently also the shaft shoulders on rotating components of compressors in machine systems. Bearing seats are all seats of bearings in/on housings or in/on shafts. Housings are all conceivable machine parts or systems which are mounted rotatably in relation to or on the shaft by means of the bearing assembly or in/on which the shafts are mounted by means of the bearing assemblies.
Axially free radial supports are bearings which either, on account of their design features, support only against radial forces/radial force components or bearings which, although also designed for receiving forces acting obliquely in relation to the bearing axis or for receiving axial forces, in particular applications are only to support against radial forces for a wide variety of reasons.
Radially free axial supports are bearings which either, on account of their design features, support only against axial forces/axial force components or bearings which, although also designed for receiving forces acting obliquely in relation to the bearing axis or for receiving radial forces, in particular applications are only to support against axial forces for a wide variety of reasons.
Bearing assemblies of this type are to be found in compressors, for example in screw-type compressors. In this bearing assembly, at least one bearing receives the radial forces and thereby rotatably supports for example the shank of a rotor against a housing. As radial supports, for example cylindrical or needle roller bearings or ball bearings are used. Also provided in the bearing assembly is at least one axial support, by means of which axial force components, occurring for example during compression, are received on the rotors. Examples of bearings of this type are ball bearings of a four-point bearing configuration and angular ball bearing configurations or tapered roller bearings.
One of the bearing assemblies is described in U.S. Pat. No. 5,975,867. The bearing assembly is formed in each case by a tapered roller bearing and a radial needle bearing. The radial needle bearing is an axial movable bearing. The tapered roller bearing is in this case exclusively intended for receiving axial forces/axial force components that are directed in the same direction as the axis of rotation of the bearing assembly. The outer rings of the two bearings considered are both respectively held in a rotationally fixed manner on a housing of the compressor. For this purpose, the outer ring of the needle bearing is pressed into a bore. The outer ring of the tapered roller bearing is rotationally fixed in relation to the housing in a form-locking manner by means of a pin. The inner rings of the bearing are seated on a shaft in a fixedly prestressed manner.
There are also known bearing assemblies in which the means for rotational securement are rotationally secured by clamping the rings against a housing or against other bearing rings in an axial force-locking manner. Alternatively, the bearing rings are secured by force locking from friction or by form locking by means of securing elements in a bore of the housing. Examples of such means for rotational securement are O-rings radially deformed between an outer ring and a bearing bore or radially deformed between a shaft and an inner ring, and consequently radially prestressing O-rings. Also used are pins and the like, which engage in a form-locking manner simultaneously in end-face recesses/bores in the bearing ring to be secured and in the housing to be secured.
The effort involved in preparing the bearing seats, for example in a housing, and in the installation of the bearing assemblies according to the prior art is relatively high. For example, the corresponding clearances/recesses for the engagement of the securing elements such as pins and O-rings must be made in the housings. During installation, the bearing rings must then be aligned precisely in such a way that the connecting elements can enter exactly into the corresponding clearances.